Impact wrench



Aug, 10, 1943. L. A. AMTSBERG IMPACT WRENCH Original Filed Nov. 22, 1939 INVENTOR [5 TEA A AMTJAYE P fl W ygm ATTORNEY.

Patented Aug. 10, 1943 mrncr WRENCH Y Lester A. Ar'ntsberg, Cleveland, Ohio, assignor to Chicago Pneumatic Tool Company, New York,

N. Y., a corporation of New Jersey Original application November 22, 1939, Serial No.

805,708, now Patent No.

1942. Divided and t 1942, Serial No.

2,285,638, dated June 9,

his application April 23, 440.174

Claims. (01. 287-119) V This invention relates to impact wrenches and more particularly to a coupling between a wrench socket and a tool head or anvil member which is arranged to receive a succession of torsional impacts for driving th socket.

The usual types of power operated wrenches include a tool head, a detachable socket receiving the end of the head, and a diametrically disposed locking pin extending through aligned holes in the socket and tool head. In the case of an im-' pact wrench, the tool head is subjected to a series of rotational hammer blows and there is a slight relative motion between the head and socket at the time of delivery of .the impact due to the slight clearance therebetween.

Among the objects of the invention are to prevent any part of the impacting torqu from being transmitted through the locking pin; to prevent the pin from becoming deformed during operation of the wrench; to permit the pin to become radially withdrawn from the head and socket at the will of the operator; and to prevent accidental removal of the pin during operation.

A feature of the invention reside in a rubber band surrounding the locking pin to serv as a retainer therefor, the rubber band being frictionally held on a recessed portion of the socket.

Other objects and features will appear more clearly from the description which follows.

In the accompanying drawing which illustrates one embodiment of the invention:

Fig. 1 is a view of the front portion of an impact wrench, chiefly in elevation, the wrench socket and a portion of the tool head being illustrated in section; and

Fig. 2 is a cross section through the tool head, socket and retainer, as indicated by the arrows 2 in Fig. 1. l s

In the illustrative embodiment of the invention, a tool head 4 is supported'for rotation in the frontend of a wrench housing 5. The tool head comprises an elongated shank 8 and an anvil portion I at the rear end thereof. The anvil portion is arranged to be driven by a power operated hammer (not shown) which drives the anvil with rotational impacts.

. The front end of the shank 8 extends forwardly from the housing and terminates at a socket engaging projection 8 of polygonal cross section fitting a correspondingly shaped opening 8 in wrench socket ill for the driven bolt or nut N. The endof the tool head and the socket have registering transverse apertures H and I2 which receive a locking pin i3. The pin is preferably a rigid cylindrical rod and serves to prevent accidental detachment of the socket from the tool head projection 8, but permits ready removal and replacement of the socket when that is desired. As it is not feasible to make. a substantially perfect fit between the socket l0 and the tool head projection 8, there is a slight amount of lost motion between these parts when a torsional impact is transmitted. In order that the entir blow may be delivered to the wrench socket direct and not through the locking pin, which might cause the latter to shear or become deformed, the pin is so mounted that it normally engages only one of the two elements that it locks, for example the tool head projection 8. This is accomplished by making the apertures l 2 in the socket larger than the aperture II which fits the pin l3.

A novel arrangement is employed for preventing accidental movement of the locking pin I3 lengthwise of its associatedbore ll. According to the invention the locking pin is secured by means of a retainer ring it of elasticmaterial, surrounding the pin and frictionally engaging a cylindrical surface on the socket member I0. It has been found that a rubber band of ordinary construction whose diameter when'untensioned is p less than that of the cylindrical portion of the socket is admirably suited for this purpose and that such a retainer does not become displaced under vibration as it has little weight and a. large amount of friction, but is adapted to be shifted manually and readily upon further stretching.

As shown in Fig. l, the rubber ring it embraces a recessed portion Illa of the socket l0. When it is desired to change the socket, the operator first removes the rubber band by stretching it over another portion 10b of larger diameter. The pin l3 may then be pushed out of the aligned holes I I and I2 to permit withdrawal of th socket in from the tool head projectionj 8. The pin I3 is readily removable as it is held only frictionally in transverse bore ll. Duel-to the clearance normally maintained betweenpin I3 andthe larger bores l2, the pin is protected from forces that would tend to deform the surface of the pin;

and prevent its removal from bore l I.

This application is a division of application Serial No. 305,708, filed November 22, 1939, Patent No. 2,285,638 granted June 9, 1942, which contains claims to aclutch.

What is claimed is:

1. In an impact tool, a locking arrangement comprising driving and driven shafts one of which fits a non-circular opening in the other, said shafts having registering apertures transas verse to said opening, a removable locking pin extending lengthwise through said apertures for securing the shafts against accidental separation, a retainer for th locking pin, said retainer comprising an elastic ring frictionally embracing the outer shaft and against which the ends of the pins are adapted to abut, the weight and inertia of said retainer being insufllcient to effect displacement thereof in response to vibrations.

2. In a wrench, a tool head having a projection substantially fitting a non-circular opening in a detachable socket, said tool head and socket having registering apertures, the apertures in the socket being slightly larger than in the tool head, a rigid pin extending lengthwise of said apertures and frictionally supported in the tool head,

' said pin serving to lock the socket against axial movement relative to the tool head, and a retainer for said locking pin, said retainer comprising a ring embracing a peripheral surface on the socket and positioned to cover the transverse apertures therein, said retainer ring being held in position by friction, the weight and inertia of said retainer being insufiicient toeffect displacement thereof in response to vibrations.

3. In a wrench according to claim 2, the retainer ring being mounted on a portion of the socket of reduced diameter and being elastic to allow it to be removed by stretching it over another portion on the socket of larger diameter.

4. In an impact wrench, a tool head having an anvil portion at its rear end adapted to receive torsional impacts and having a projection at its front end substantially fitting a non-circular opening in a detachable socket, said tool head and socket having registering apertures, the apasaasiv ertures in the socket being slightly larger than in lengthwise of said apertures and fitting the aperture in the'tool head, said pin serving to lock the socket against axial movement relative to the tool head but normally held out of driving engagement with the socket, and a retainer for said locking pin, said retainer comprising a tensioned rubber band embracing a peripheral surface on the socket and positioned to cover th transverse apertures therein, said retainer ring being held in position by friction, the weight and inertia of said retainer being insufficient to effect displacement thereof during the delivery of torsional impacts.

5. In a rotary impact tool, a tool head having an anvil portion at its rear end adapted to receive torsional impacts and having a square projection at its front end substantially fitting a complementary opening in a detachable socket, said tool head and socket having registering apertures extending radially, a rigid pin extending through said apertures and serving to lock the socket against axial movement relative to the tool head, and a retainer for said locking pin, said res tainer comprising an initially tensioned rubber band embracing a peripheral surface on the socket and engageable with the locking pin, the weight and inertia of said retainer being insufficient to effect displacement thereof during the delivery-of torsional impacts, said ring being quickly detachable from the socket bybeing grasped manually and stretched beyond its initial tension.

LESTER A. AMTSBERG. 

